During an NPA split, one or more new NPAs are created and assigned to an area formerly having only a single assigned NPA. The process of assigning new NPAs to all of the affected telephone lines occurs over a period of time. During this time, which is referred to as the permissive dialing period, calls can be placed to a telephone line using either the old or new NPA. In some networks, call processing records are duplicated during the permissive dialing period. The original call processing record is identified by the telephone number with the old NPA, and the duplicate call processing record is identified by the telephone number with the new NPA. Problems can arise when changes are made to one call processing record but not the other during the permissive dialing period.
Several approaches have been discussed to solve this problem. One approach is described in U.S. Pat. No. 5,978,462. With the approach described in the '462 patent, all call processing records identified by telephone numbers with old NPAs are modified to include a pointer to call processing records identified by telephone numbers with new NPAs. Another approach is described in U.S. Pat. No. 6,289,095. Under this approach, pertinent parameters of all incoming query messages are changed in the network signaling interface of the SCP to replace the old NPA with the new NPA before the message is sent to the application level software of the SCP. This approach can result in undue extra processing time as not all messages may need to have the old NPA replaced with the new NPA.
There is a need, therefore, for a new method for NPA split processing on a service control point.